The sustained presence of northern red oak (Quercus rubra) in forested ecosystems often depends upon seed-origin reproduction. This is particularly true on highly productive sites. Although concern has been raised regarding the ability of northern red oak to successfully regenerate from seed, most research has focused on the inability of small oak seedlings to become well-established advanced regeneration. The mechanisms involved in the initial establishment of seedlings are often disregarded because in most reported cases small seedlings are present, but advanced regeneration greater than 15 cm tall is absent. It is generally believed that the stock of small oak seedlings builds up slowly as small numbers of acorns escape vertebrate predation and insect infestation during years of heavy seed production. However, in parts of the central hardwood region, small northern red oak seedlings may be sparse or absent for extended periods. The problem is particularly common in the central Appalachians where, rather than building up slowly, seedlings appear to become established in single-cohort waves during anomalous years of abundant acorn production and favorable weather conditions.

During the seminar, I will present an overview of twelve years of northern red oak establishment research conducted in the central Appalachians. My conclusions to date include the following:

1. Almost 60% of initially sound, insect-free, northern red oak acorns germinated and produced seedlings when they were protected from vertebrates.

2. Less than 7% of unprotected or partially protected acorns survived to germinate; the rest were removed from beneath parent trees by vertebrate predators. When deer, turkey, and other large vertebrates were excluded, small mammals removed over 80% of northern red oak acorns within 21 days of sowing. The remaining acorns were removed slowly over the course of the winter.

3. Small mammals may remove acorns faster when the acorn crop is larger. Rather than satiating vertebrate predators, large acorn crops may actually stimulate more intense predation.

4. Insects that lay their eggs in acorns as they develop on the tree can infest a majority of the acorn crop. Curculio weevil larvae infested over 8,000 of the 18,000 acorns dissected in one year of study. Other insects, such as gall-forming wasps and moth larvae may be found in much smaller numbers in autumn collections of northern red oak acorns.

5. Although small numbers of Curculio-infested acorns may germinate, very few produce viable seedlings. However, Curculio infestation does not significantly predispose acorns to secondary insects or disease.

6. In years when conditions are favorable for rapid seedling growth, spring infestations of Conotrachelus weevils and moth larvae may not significantly impair germination or seedling establishment. However, during warm, dry springs, insects can destroy the entire crop of new seedlings.

7. Although burying acorns 1 inch deep provides some protection from drying and insect infestation, burial does not protect acorns from small vertebrates and results in a significantly higher incidence of fungi and disease.

By the time of presentation, I also will have analyzed additional research on the effects of site quality and fungi on seedling establishment.